Phosphated mixed esters of hydroxy amines

ABSTRACT

Phosphate mixed esters of hydroxy amines containing less than eight carbon atoms in hydrocarbon groups attached to the amino nitrogen and hydroxy hydrocarbons containing at least six carbon atoms in a hydrocarbon group thereof are prepared and used as scale inhibitors.

United States Patent 1 Stanford et al.

[ PHOSPHATED MIXED ESTERS OF HYDROXY AMINES [75] Inventors: James R.Stanford, Sugarland; Paul G. Vogelsang, Jr., Houston, both of Tex.

[73] Assignee: Nalco Chemical Company, Chicago,

111. 221 Filed: Feb. 3, 1970 I 211- Appl. N0.: 8,436

Related U.S. Application Data [62] Division of Ser. No. 682,618, Nov.13, 1967, Pat. No.

[4 1 Apr. 17, 1973 [56] References Cited UNITED STATES PATENTS 3,380,9274/1968 Edelstcin et al. ..260/928 X Primary Examiner-Lewis GottsAssistant Examiner-Anton H. Sutto Attorney-.1ohn'ston, Root," OKeeffe,Keil, Thompson and Shurtlefi" v 7 ABSTRACT Phosphate mixed esters ofhydroxy amines containing less than eight carbon atoms in hydrocarbongroups attached to the amino nitrogen and hydroxy hydrocarbonscontaining 'at least six carbon atoms in a hydrocarbon group thereof areprepared and 'used as scale inhibitors,

7 Claims, No Drawings PHOSPH ATED MIXED ESTERS OF HYDROXY AMINES Thisapplication is a division of U.S. application Ser. No. 682,618, filedNov. 13, 1967 which has now matured into U.S. Pat. No. 3,557,001.

The preferred compositions of the invention are phosphate mixed estersof: (A) hydroxy amines con taining less than eight carbon atoms inhydrocarbon groups attached to one or more amino nitrogens, and (B)oxyalkylated monohydroxy surface active compounds, e.g., oxyethylatednonylphenol, oxyethylated tridecyl alcohol, and oxyethylated normalalcohol mixtures containing six or more carbon atoms.

The hydroxy amines and the hydroxy hydrocarbons are phosphated byreaction with polyphosphoric acid or phosphorus pentoxide at elevatedtemperature, preferably in the order of about 50 to 175C. The reactiontime is preferably at least about 30 minutes. The reaction may beconducted longer, however, e.g.-, up to 3 to 5 hours, to assure completereaction. If desired, a catalyst such as BF etherate complex may beused. When using polyphosphoric acid, the hydroxy amine and the hydroxyhydrocarbon can be added to the polyphosphoric acid liquid. Conversely,the polyphosphoric acid can be added to a mixture of the hydroxyamineand the hydroxy hydrocarbon.

The resultant reaction product may be used as is, or it may be convertedto a salt by partial to complete neutralization with an alkalinesubstance such as, for example, potassium or sodium hydroxide, potassiumor sodium carbonate, ammonia, or a basic amino compound, e.g.,tetramethyl ammonium hydroxide, methylamine, ethylamine, diethylamine,triethanolamine, diethanolamine, tn'ethylamine, ethylene diamine,diethylene triamine, pyridine, morpholine or other amine. The amineshould preferably be a water soluble amine or at least one that does notdestroy solubility in water.

The hydroxy amines can be relatively simple amines, such as,diethanolamine or triethanolamine, or they can be more complex, such as,the still residues obtained in the manufacture of triethanolamine or theproducts obtained by oxyalkylating amines. They can be monoamines orpolyamines. They can have a single hydroxy group as inaminoethylethanolamine but preferably have a plurality of hydroxygroups. The oxyalkylated amines are obtained by reacting an alkyleneoxide, for example, ethylene oxide or 1,2-propylene oxide, with an aminecontaining one or more reactive hydrogen atoms. The preferred aminescontain at least one 2-hydroxy ethyl group (--CH,CH,OH) provided byoxyethylation. The primary hydroxyl groups thereof are more effectivethan the secondary hydroxyl groups which would be provided byoxypropylation Cll Tlb-Oll) Ulla However, oxypropylation may be used ifthe oxypropylated product is then oxyethylated to provide terminalZ-hydroxyethyl groups. Ethylenediamine, for example, can be oxyethylatedwith 4 moles of ethylene oxide per mole of diamine to produce a diaminecon-- as 30 moles of alkylene oxide per mole of amine. In general,however, this is not necessary for the purpose of the invention. Otheramines which can be oxyalky lated to provide hydroxy amines arediethylenetriamine, triethylenetetramine and tetraethylene pentamine. Itis normally desirable that the hydroxy group which is to be phosphatedshould be separated from the nitrogen atom by at least one carbon atomand preferably by at least two carbon atoms as in the 2-hydroxyethylgroup. Amines of this general structure are sometimes referred to ashydroxyalkyl amines or alkanolamines. It will be understood thatmixtures of hydroxy amines as well as individual amines can be employedin preparing the phosphate esters. Hence, the products can consist ofmixed phosphate esters and mixtures of phosphate esters of the hydroxyamines.

The preferred hydroxy hydrocarbons are monohydric surface active agentsderived by the oxyethylation of alkyl phenols, e.g., containing four to12 carbonatoms in the alkyl group or groups, preferably nonyl phenol ordinonyl phenol or mixtures thereof, or primary alcohols containing sixto 18 carbon atoms, preferably tridecyl alcohol, or mixed 6-10 carbonatoms alcohols, with 2-20, preferably 4-14 moles of ethylene oxide permole of such monohydric substance.

in general, it is preferable that the monohydric oxyalkylated surfaceactive agent have a terminal 2-hydroxyethyl group provided byoxyethylatio'n. The primary hydroxyl groups are more effective than thesecondary hydroxyl groups which would be provided by oxypropylation.However, oxypropylation or oxybutylation can be used if the oxyalkylatedproduct is then oxyethylated to provide terminal Z-hydroxyethyl groups.

The phosphate esters have an average of at least one and up to all ofthe hydroxyls of the organic portion of the molecule replaced byphosphate ester groups derived from phosphorus pentoxide orpolyphosphoric acid, the said phosphate ester groups consistingessentially of one or both of a member selected from the groupconsisting of Also, the invention embraces the salts derived by thepartial to complete neutralization of the phosphate ester groups.

The invention further embraces a process for preventing hardness scaledeposits on metal surfaces in contact with hard water containinghardness scale-- forming ions which comprises contacting said metalsurfaces with said hard water while maintaining therein ahardness-ionprecipitation-pmventing quantity in the order of 05-100parts per million of the previously described mixed esters and saltsthereof.

The invention is particularly suitable for scale prevention by naturalbrines on ferrous metal walls and other surfaces in oil producing andwater flood systems. Inorganic polyphosphates have long been the mosteffective and economical sequestering agents used for the prevention ofalkaline deposits in both oil producing and water flood systems.However, due to the problems encountered in feeding polyphosphates andtheir incompatibility with many waters, a need for a liquid organicphosphate with good solubility in waters containing hardness ions hasbecome increasingly evident. For this reason, a liquid inorganic productwith good solubility in produced waters and having the effectiveness andlow treating cost of inor ganic polyphosphates is needed.

The invention has utility in the prevention of similar scale depositsoccurring in closed and once-throughcooling systems where hard water isemployed.

The compounds may also have utility in boiler feed waters and in waterscharged to certain desalinization 7 equipment where scale deposition isa problem.

The invention may also be used in the prevention of scale deposits incertain effluent and disposal waters, particularly wehre other materialsused in the prevention of such deposits may constitute a pollutionproblem.

The invention is especially important in the treatment of wells in whatis known as a squeeze" application. The chemicals of the invention haveunique adsorption-desorption properties in that they are adsorbed onsolid surfaces and slowly released into the produced water or brine overa period of time to give long term protection caused by scale depositionin the surfaces of the formation face and the producing equipment.

The mixed phosphate esters of the invention are liquid materials with alow freezing point and good solubility in brines. They have advantagesover some mixed phosphate esters which have been previously proposedthat are derived from polyols and monohydric non-ionic surface activeagents.

The invention will be further illustrated but is not limited by thefollowing examples in which the quantities are stated in parts by weightunless otherwise indicated.

EXAMPLE I EXAMPLE II 300 parts of a still residue obtained in themanufacture of triethanolamine (Amine N-l) were mixed with 150 parts ofthe oxyethylated tridecyl alcohol described in Example 1 and the mixtureheated to 50C. 700 parts of polyphosphoric acid were then added whileallowing the temperature of the mixture to increase to 130-140C. Thereaction mixture was then cooled to below 100C. and 700 parts wateradded.

EXAMPLE Ill 150 parts of a triethanolamine still residue (Amine N-l)were mixed with 150 p arts of a mixture of aliphatic alcohols (Alfol610) containing 20 percent hexanol, 35 percent octanol and the remainderdecanol. This mixture was heated to 50C. and 700 parts polyphosphoricacid were slowly added while allowing the temperature to increase to130140C. The mixture was held at 130140C. for 30 minutesafter thepolyphosphoric acid addition was complete. It was then cooled to 95C.and 500 parts of water and 700 parts of normal propanol were added.

EXAMPLE IV 150 parts of triethanolamine still residue (Amine N-l) weremixed with 150 parts oxyethylated tridecyl alcohol (30.7 percenttridecyl alcohol plus 69.3 percent ethylene oxide) and the mixtureheated to 50C.

' 500 parts of polyphosphoric acid were slowly added to the mixturewhile allowing the temperature to increase to 130-140C. The mixture washeld at 130140C. for 30 minutes after the polyphosphoric acid additionhad been completed. It was then cooled to. C. and 400 parts of wateradded.

EXAMPLE V The procedure was the same as in Example IV except that thepolyphosphoric acid was placed in a 3-necked reaction flask providedwith agitation and heated to 50C. Thereafter the heat was discontinuedand the mixture of hydroxy amine and oxyethylated tridecyl alcoholheated to 50C. was added gradually while allowing the temperature toincrease to 130C. The temperature was then held at 130C. for 30 minutes,the mixture thereafter cooled to 95C. and 400 parts of water were added.

EXAMPLE VI The procedure was the same as in Example III except that themixture of hydroxy amine and Alfol 610 was added to the polyphosphoricacid.

EXAMPLE VII 150 parts of triethanolamine still residue (Amine N-l) weremixed with 150 parts oxyethylated nonyl phenol (32.5 percent nonylphenol plus 67.5 percent ethylene oxide) and 500 parts polyphosphoricacid were slowly added to the mixture while allowing the temperature toincrease to 130C. The temperature was held at 130C. for 30 minutes afterwhich the mixture was cooled to 95C. and 400 parts of water were added.

EXAMPLE VIII 250 parts polyphosphoric acid were heated to 50C. and amixture of 75 parts Amine N-l and 75 parts oxyethylated phenol (55.6percent nonyl phenol plus 44.4 percent ethylene oxide) was added slowlywhile allowing the temperature of the reaction mixture to increase to130C. The reaction mixture was heated at 130C. for 30 minutes and thencooled below C. Thereafter 200 parts of water and 50 parts of normalpropanol were added.

EXAMPLE IX 500 parts of polyphosphoric acid were heated to 50C. and amixture of 30 parts Amine N-l and 30 parts Alfol 1218 (monohydricmixture containing 62 percent hexadecanol and 35 percent octadecanol wasadded slowly while allowing the temperature to rise to 7 C. The reactionmixture was held at a temperature of 130C. for 30 minutes, then cooledto below 100C. and 150 parts water and 125 parts normal propanol wereadded.

EXAMPLE x 250 parts polyphosphoric acid were heated to 50C. and amixture of 75 parts tetrahydroxyethylethylenediamine and 75 partsoxyethylated tridecyl alcohol (30.7 percent tridecyl alcohol'plus 69.3percent ethylene oxide) was added slowly while allowing the temperatureof the mixture to rise to 7 130C. The temperature of the reactionmixture was held at 130C. for 30 minutes. The mixture was then cooled tobelow 100C. and 200 parts of water were added.

EXAMPLE XI 250 parts of polyphosphoric acid were heated to 50C. and amixture of 75 parts tetrahydroxyethylethylenediamine and 75 partsoxyethylated nonyl phenol (32.5 percent nonyl phenol plus 67.5 percentethylene oxide) was slowly added while allowing the temperature of themixture to increase to 130C. The temperature of the mixture was held at130C. for 30 minutes. The mixture was then cooled and 200 parts of wateradded. 1

EXAMPLE XII I 250 parts polyphosphoric acid were heated to 50C and amixture of 75 parts tetrahydroxyethylethylenediamine and 75 partsoxyethylated nonyl phenol (55.6 percent nonyl phenol plus 44.4 percentethylene oxide) was added slowly while allowin the reaction temperatureto increase to 130C. The temperature was held at 130C. for 30 minutes,then cooled and 200 parts water and parts normal propanol were added.

EXAMPLE XIII 250 parts polyphosphoric acid were heated to 50C. and amixture of 75 parts tetrahydroxyethylethylenediamine and 75 partstridecyl alcohol was added slowly while allowing the temperature of ofthe reaction mass to increase to 130C. The reaction mixture was held at130C. for minutes, then cooled and 200 parts water and 50 parts normalpropanol added.

EXAMPLE XIV 250 parts polyphosphoric acid were heated to 50C. and amixture of 75 parts triethanolamine still residue (Amine N-l) and 75parts tridecyl alcohol was added slowly while allowing the reactiontemperature to increase to 130C. The temperature of the mixture was heldat 130C. for 30 minutes. The mixture was then cooled and 200 parts waterand 75 parts normal propanol added.

EXAMPLE XV 250 parts polyphosphoric acid were heated to 50C. and amixture of 75 parts tetrahydroxyethylethylenediamine and 75 parts Alfol610 was added slowly while allowing the reaction temperature to increaseto 130C. The temperature of the reaction mixture was held at 130C.'for30 minutes. The mixture was then allowed to cool and 200 parts water and75 parts normal propanol added.

EXAMPLE XVI 250 parts polyphosphoric acid were heated to C. and amixture of 75 parts tetrahydroxyethylethylethylenediamine and 75 partsAlfol 1218 was added slowly while allowing the temperature of themixture to increase to 130C. The temperature of the mixture was held at130C. for 30 minutes. The mixture was then cooled and 200 parts waterand 50 parts normal propanol were added. 9

EXAMPLE XVII 200 parts of the product of Example V were mixed with 75parts water and 100 parts 50 percent aqueous caustic soda.

EXAMPLE XVIII 200 parts of the product of Example V were mixed with 25parts water and 150 parts of Amine N-1.

EXAMPLE XIX 200 parts of the product of Example V were mixed with 50parts water and 150 parts Amine C-6.

EXAMPLE XX 1 250 parts of polyphosphoric. acid were heated to 50C. and amixture of 75, parts Amine N-l and 75 parts oxyethylated tridecylalochol (11.1 percent tridecyl alcohol plus 89.9 percent ethylene oxide)was added slowly while allowing the temperature to increase to 130C. Thetemperature was held at 130C.

for 30 minutes. The reaction product was then cooled and 200 parts ofwater added.

EXAMPLE XXI 250 parts of polyphosphoric acid were heated to 50C. and amixture of 75 parts Amine N-1 and 75 parts of oxyethylated nonyl phenol(10.7 percent nonyl Yphenol plus 89.3 percent ethylene oxide) was addedslowly while allowing the reaction temperature to increase to 130C.After heating at this temperature for 30' minutes, the reaction productwas cooled and 200 parts of water added.

EXAMPLE XXII EXAMPLE XXIII 200 parts polyphosphoric acid were heated to50C. and' a mixture of parts tetrahydroxyethylethylenediamine and 75parts oxyethylated nonyl phenol (10.7 percent nonyl phenol plus 89.3percent ethylene oxide) was added slowly while allowing the reactiontemperature to increase to 130C. The reaction mixture was held at 130C.for 30 minutes, then cooled and 200 parts of water added.

EXAMPLE XXIV The procedure was the same as in Example V except that theproduct was diluted with normal propanol and water. In the resultantproduct, the polyphosphoric acid constituted 21.4 percent theoxyethylated tridecyl alcohol 6.4 percent, the triethanolamine residue6.4 percent, water-50.4 percent and normal propanol 15.4 percent. Theactive component was therefore 34.2 percent.

In the foregoing examples, the phosphation was carried out with 115%polyphosphoric acid. Phosphorus pentoxide or mixtures of polyphosphoricacid and phosphoric acid and phosphorus pentoxide can also be used.However, the reaction is smoother with polyphosphoric acid and is mucheasier to control.

The compositions of the invention are especially effective in theinhibition of scaling on metal surfaces by calcium sulfate, bariumsulfate, and calcium carbonate. They are useful in the oil productionindustry to prevent deposits of these scale-producing compounds on metalsurfaces of pumps, pipes, valves, tanks, and the like, when waterscontaining the scale-producing compounds (or precursors thereof, e.g.,calcium bicarbonate) are treated in the concentrations aforesaid, i.e.,0.5 to 100 parts per million. Places where scale build up is most likelyto become troublesome are those in the liquid handling systems whereinthere is a change in fluid pressure, a change in fluid temperature, or achange in fluid flow rate.

The invention may be used may be used in waterflood systems used toinject water into subterranean formations, wherein the water is brackishor is a brine conducive to scale formation on metal surfaces of thewaterflood system. Typcial brines encountered in waterflood operations,wherein water is drawn from sources available at or near the waterfloodsite, are:

Brine A Brine B Chloride (NaCl) 49,000 mg/l. 28,000 mg/l. Total Hardness(CaCO;,) 5,300 mg/l. 3,400 mg/l. Calcium (CaCO;) 4,900 mg/l. 1,600 mg/,.Alkalinity P(CaCO,) 120 mg/l. 80 mg/l. Alkalinity M(CaCO 1,050 mg/l. 130mg/l. Sulfate (NaSOJ 4,750 mg/l. pH 7.8 8.3

Any of the products previously described can be used to prevent scaleformation on metal walls of pipes, pumping equipment and storage tanksused to inject flood waters into subterranean formations. The dosagewill vary depending on the particular composition and the type of brinein the formation but, in general, effective control is obtained with to20 parts per million (ppm) of inhibitor and in some cases as low as 0.5ppm iseffective.

1n cooling waters of closed cooling systems, wherein the cooling wateris a typical municipal tap water,

maintenance of dosage levels of 15-30 ppm are typical, 1

The compositions of the invention are useful in a number of areas wherescaling of metal surfaces, particularly ferrous metal surfaces, bybarium sulfate, calcium sulfate and/or calcium carbonate is a problem.By control of scale formation, breakdowns, maintenance, cleaning andrepairs caused or necessitated by scale formations can be minimized.

In comparative tests using brines made by dissolving 7.5 grams of sodiumchloride and 8.33 grams of calcium chloride in distilled watersufficient to make 1 liter (Brine C) and 7.5 grams sodium chloride plus10.66 grams Na SO in distilled 'water sufficient to make 1 liter (BrineD), it was found that the composition of Example XXIV was partiallyeffective in preventing calcium sulfate deposition at 0.25 ppm andcompletely effective at 1 ppm when 50 ml of each brine were mixed andheated for 24 hrs., at F. A control test with no additive gave a depositof 1,800 ppm CaSO calculated as CaCO The compositions of Example XXIValso prevented barium sulfate precipitation over a period of 20 hours ata temperature of 160C. using concentrations of said composition of l-l0ppm in a solution having a barium concentration of 160 mg/l as bariumchloride and a sulfate concentration of 1600 mg/l as sodium sulfate.

The composition of Example XXIV was also effective in preventing calciumcarbonate depositions on the surface of test cells containing 20 ml ofbrine (Brine E) made by dissolving 5,180 mg/l sodium bicarbonate, 22,200mg/l sodium chloride, 6 mg/] sodium sulfate (Na- SO 366 mg/l magnesiumchloride (MgCl -6H O), and 2,000 mg/l calcium chloride, having a pH of6.2, saturated with carbon dioxide before use, and heated for 20 hoursat 160C. Complete inhibition of calcium carbonate deposition wasobtained at a dosage of 3 ppm. The blank control deposited 1,460 mg/l ofcalcium carbonate.

In a similar manner, the products of Examples VIII to XIX were evaluatedand it was found that all of these products were effective in retainingcalcium sulfate in solution in a mixture of 50 ml of Brine C and 50 mlof Brine D at a temperature of 160F. under static conditions for 24hours. In these tests the blank, before precipitation, contained 4,800mg/l of calcium sulfate, as calcium carbonate, and after precipitation3,000 mg/l of calcium sulfate, as calcium carbonate. The addition of 1ppm, 2 ppm, 3 ppm, 5 ppm and 10 ppm of tained 4,900 mg/l of calciumsulfate, as calcium carbonate, and 3,200 mg/l after precipitation, theaddition of 1 ppm, 3 ppm, 5 ppm and 10 ppm of each of the products ofExamples XX, XXI, XXII and XXIII caused the retention of all of thecalcium sulfate. The addition of 0.5 ppm of the product of Example XXcaused the retention of 4,600 mg/l of the calcium sulfate, calculated ascalcium carbonate, and the addition of 0.5 ppm of the products ofExamples XXI, XXII and XXIII caused retention of all of the calciumsulfate.

In a calcium carbonate brine of the type previously described, heated toa temperature of 160C. under static conditions for 24 hours where theblank control before precipitation contained 1,840 mg/l of calciumcarbonate and after precipitation 400 mg/l of calcium carbonate, theaddition of as little as 1 ppm of each of the compositions of ExamplesVIII to XIX produced some retention of the calcium carbonate and theaddition of 20 ppm produced complete retention of the calcium carbonate.In the case of Examples XI and XVI, complete retention was obtained at aconcentration of 5 ppm.

In a similar test over a period of hours, the compositions of ExamplesXX to XXIII provided complete retention of the calcium carbonate at 3ppm concentration. The products of Examples XXI, XXII and XXIII alsoafforded complete retention at a concentration of 1 pp I In the processfor makingphosphate esters previously described, it will be understoodthat where a solvent is used the process is carried out at a temperaturebelow the boiling point of the solvent.

The solvents used act as combination solvents and viscosity controlagents, although any solvents, e.g., hydroxyacetic acid, having areactive hydroxyl group will react in the phosphation and influence theoverall composition of the final product.

In a number of oil fields in West Texas and other areas, water floodshave been established in which waters incompatible with the connatewaters were used for injection. This occurs when a good source ofcompatible water is not available. Most of these floods are using a highsulfate water to flood a formation which has a high calcium contentwater. As the watersreach the producing well they mix, and a calciumsulfate deposition occurs, either in the formation at the well boreor inthe producing equipment. This requires the removal of the tubing,rodsand pump for cleaning, and a fracturing job if-the formationisplugged, which is the case most of the timeeBy the practice of thepresent invention the formation'of scale in the producing equipment andunderground formation can be reduced or prevented. However, as the scaleforms in the producing formation, the scale control chemical must besqueezed into theproducing undergroundformation so it can be producedback slowly mom of the waters before they mix. To give long term scaleinhibttion the chemical must be adsorbed on the underground formation insuch a manner that it is slowly released into the water as it passesover the formation so that a chemical concentration of 1 to 10,000 ppmis alwaysin the water. Some scale control compounds when squeezed intothe formation are so tightly absorbed that little, if any, feedbackoccurs, while others are essentially not Similarly, the invention isapplicable to the treatment of water supply wells. The pre-addition ofwater to the well can be omitted. The phosphate mixed esters or mixtureof esters can also be added directly to the input well of a waterfloodsystem consisting of one or more input wells and one or more producingwells.

adsorbed and feedback occurs immediately with no ex- I As previouslyindicated, the chemical compositions prepared as herein described areespecially valuable because of their adsorption-desorption propertieswhich makes it possible to be adsorbed on solid surfaces and slowlyreleased into the produced water or being over a period of time to givelong term protection against scale deposition. a

In practicing the invention it will be understood that a number ofmodifications can be made in the preparation of the phosphate esters.The esterification process can be carried out with or without theaddition of a solvent. Examples of solvents are isopropanol, n-

propanol, dioxane and toluene. If a solvent is used, the

process is normally carried out at temperatures below the boiling pointof the solvent.

In the description it will be understood that the term hydroxyhydrocarbon is intended to cover hydrocarbons where the hydroxyl groupis attached directly to a carbon group of at least six carbon atoms, aswell as oxyalkylated derivatives thereof wherein the hydroxyl group isconnected to a carbon chain which in turn is connected through oxygen toa hydrocarbon group. In the latter event, the oxyalkylated material cancontain a plurality of ether oxygen atoms, dpending upon the degree ofoxyalkylation.

An important feature resides in the fact that the compositions of theinvention are effective in inhibiting the precipitation of hardnesscomponents of water, such as calcium, when such compositions are used inwhat is commonly referred to as threshold amounts, i.e., usually 1 to 3parts per million and not more than 9 parts per million. These amountsare far less than normally required to sequester or chelate the calcium.7

Another important feature is the stability of the compositions againsthydrolytic action at high temperatures. For example, they can be used toinhibit scale formation in water or brines at 200-300F. where inorganicpolyphosphates are relatively unstable. They can also be used underconditions where much higher temperatures are employed, for instance,-inwater or brines which are heated by submerged combustion.

In addition, the compositions of the invention can act as corrosioninhibitors in corrosive waters and brines.

The compounds which are described by trade name have the followingcompositions:

l. Amine N-l is an amine residue obtained in the production oftriethanolamine.

2. Amine C-6, obtained as a co-product froma commercial continuousoperation, is a clear, dark-amber liquid composed primarily of a mixtureof aliphatic and heterocyclic monoand diamines. The morpholinyl ring isthe dominant heterocyclic group present, and the oxyethylene linkageappears very frequently in the various compounds present. Amine C-6 iscompletely miscible with water. The principal components of Amine C-6are 4-(2-aminoethoxy) ethyl morpholine, 2-(4-morpholinylethoxy) ethanoland morpholinyl) ethyl ether.

The invention is hereby claimed as follows:

bis-2-(4- l. A phosphate mixed ester obtained by the reactionpolyphosphoric acid and phosphorus pentoxide with at least one hydroxyamine and at least one hydroxy hydrocarbon at temperatures from about 50to 175C. in proportions and for a period of time such that hydroxylgroups of both said hydroxy amines and said hydroxy hydrocarbons arereplaced by phosphate ester groups, said phosphate ester groupsconsisting essentially of one or both of a member selected from thegroup consisting of said hydroxy amine being from the group consistingof tetrahydroxyethylethylene diamine and triethanolamine still residuesand said hydroxy hydrocarbons being from the group consisting ofoxyethylated monohydric alkyl phenols containing four to 12 carbon atomsin the alkyl group or groups and oxyethylated monohydric alkyl alcoholscontaining six to 18 carbon atoms, said oxyethylated alkyl phenols andsaid oxyethylated alkyl alcohols containing 2 to 20 moles of ethyleneoxide per mole thereof, the weight ratio of said hydroxy amine to saidhydroxy hydrocarbon being within the range of 1:2 to 2: l.

2. A water soluble salt derived by the partial to completeneutralization of said phosphate ester groups ofa composition as claimedin claim 1.

3. A phosphate mixed ester as claimed in claim I wherein saidhydroxyamine is a triethanolamine still residue.

4. A phosphate mixed ester as claimed in claim 1 wherein saidhydroxyamine is tetrahyd'roxyethylethylenediamine.

5. A phosphate mixed ester as claimed in claim 1 wherein said hydroxyhydrocarbon is an oxyethylated alkyl phenol containing 4-12 carbon atomsin an alkyl group oxyethylated with about 2-20 moles of ethylene oxideper mole of said alkyl phenol.

6. A phosphate mixed ester as claimed in claim 1 wherein said hydroxyhydrocarbon is derived by oxyethylation of tridecyl alcohol with about2-20 moles of ethylene oxide per mole of tridecyl alcohol.

7. A phosphate mixed ester as claimed in claim 1 wherein said hydroxyhydrocarbon is an oxyethylated mixture or primary alkyl alcoholscontaining four to 12 carbon atoms.

2. A water soluble salt derived by the partial to completeneutralization of said phosphate ester groups of a composition asclaimed in claim
 1. 3. A phosphate mixed ester as claimed in claim 1wherein said hydroxyamine is a triethanolamine still residue.
 4. Aphosphate mixed ester as claimed in claim 1 wherein said hydroxyamine istetrahydroxyethylethylenediamine.
 5. A phosphate mixed ester as claimedin claim 1 wherein said hydroxy hydrocarbon is an oxyethylated alkylphenol containing 4-12 carbon atoms in an alkyl group oxyethylated withabout 2-20 moles of ethylene oxide per mole of said alkyl phenol.
 6. Aphosphate mixed ester as claimed in claim 1 wherein said hydroxyhydrocarbon is derived by oxyethylation of tridecyl alcohol with about2-20 moles of ethylene oxide per mole of tridecyl alcohol.
 7. Aphosphate mixed ester as claimed in claim 1 wherein said hydroxyhydrocarbon is an oxyethylated mixture or primary alkyl alcoholscontaining four to 12 carbon atoms.